System and method for content protection on a computing device

ABSTRACT

Systems and methods for handling user interface field data. A system and method can be configured to receive input which indicates that the mobile device is to enter into a protected mode. Data associated with fields displayed on a user interface are stored in a secure form on the mobile device. After the mobile device leaves the protected mode, the stored user interface field data is accessed and used to populate one or more user interface fields with the accessed user interface field data for display to a user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication Ser. No. 60/567,080, filed on Apr. 30, 2004, of which theentire disclosure (including any and all figures) is incorporated hereinby reference.

TECHNICAL FIELD AND BACKGROUND

This document relates generally to the field of communications, and inparticular to protecting content on computing devices.

Mobile devices contain user interfaces for users to interact with themobile device. Users can both view and input data through data fieldsprovided through the mobile devices' user interfaces. However, a mobiledevice's field data may not be able to be handled effectively and/orefficiently when the mobile device is entering or has entered aprotected mode (e.g., a locked state).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of an example communication system in which awireless communication device may be used.

FIG. 2 is a block diagram of a further example communication systemincluding multiple networks and multiple mobile communication devices.

FIG. 3 is a block diagram depicting user interface fields that appear onuser interface screen(s) of a mobile device.

FIGS. 4 and 5 are block diagrams depicting protection of content locatedon user interface screens.

FIG. 6 is a flowchart illustrating an example of an operational scenariofor handling user field data on a mobile device.

FIGS. 7 and 8 are flowcharts illustrating an example of an operationalscenario for creating encryptable fields in order to protect content.

FIG. 9 is user interface screen displayed to a user of a mobile device.

FIG. 10 is a block diagram of an example mobile device.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overview of an example communication system in which awireless communication device may be used. One skilled in the art willappreciate that there may be hundreds of different topologies, but thesystem shown in FIG. 1 helps demonstrate the operation of the encodedmessage processing systems and methods described in the presentapplication. There may also be many message senders and recipients. Thesimple system shown in FIG. 1 is for illustrative purposes only, andshows perhaps the most prevalent Internet e-mail environment wheresecurity is not generally used.

FIG. 1 shows an e-mail sender 10, the Internet 20, a message serversystem 40, a wireless gateway 85, wireless infrastructure 90, a wirelessnetwork 105 and a mobile communication device 100.

An e-mail sender system 10 may, for example, be connected to an ISP(Internet Service Provider) on which a user of the system 10 has anaccount, located within a company, possibly connected to a local areanetwork (LAN), and connected to the Internet 20, or connected to theInternet 20 through a large ASP (application service provider) such asAmerica Online (AOL). Those skilled in the art will appreciate that thesystems shown in FIG. 1 may instead be connected to a wide area network(WAN) other than the Internet, although e-mail transfers are commonlyaccomplished through Internet-connected arrangements as shown in FIG. 1.

The message server 40 may be implemented, for example, on a networkcomputer within the firewall of a corporation, a computer within an ISPor ASP system or the like, and acts as the main interface for e-mailexchange over the Internet 20. Although other messaging systems mightnot require a message server system 40, a mobile device 100 configuredfor receiving and possibly sending e-mail will normally be associatedwith an account on a message server. Perhaps the two most common messageservers are Microsoft Exchange™0 and Lotus Domino™. These products areoften used in conjunction with Internet mail routers that route anddeliver mail. These intermediate components are not shown in FIG. 1, asthey do not directly play a role in the secure message processingdescribed below. Message servers such as server 40 typically extendbeyond just e-mail sending and receiving; they also include dynamicdatabase storage engines that have predefined database formats for datalike calendars, to-do lists, task lists, e-mail and documentation.

The wireless gateway 85 and infrastructure 90 provide a link between theInternet 20 and wireless network 105. The wireless infrastructure 90determines the most likely network for locating a given user and tracksthe user as they roam between countries or networks. A message is thendelivered to the mobile device 100 via wireless transmission, typicallyat a radio frequency (RF), from a base station in the wireless network105 to the mobile device 100. The particular network 105 may bevirtually any wireless network over which messages may be exchanged witha mobile communication device.

As shown in FIG. 1, a composed e-mail message 15 is sent by the e-mailsender 10, located somewhere on the Internet 20. This message 15 isnormally fully in the clear and uses traditional Simple Mail TransferProtocol (SMTP), RFC822 headers and Multipurpose Internet Mail Extension(MIME) body parts to define the format of the mail message. Thesetechniques are all well known to those skilled in the art. The message15 arrives at the message server 40 and is normally stored in a messagestore. Most known messaging systems support a so-called “pull” messageaccess scheme, wherein the mobile device 100 must request that storedmessages be forwarded by the message server to the mobile device 100.Some systems provide for automatic routing of such messages which areaddressed using a specific e-mail address associated with the mobiledevice 100. In a preferred embodiment described in further detail below,messages addressed to a message server account associated with a hostsystem such as a home computer or office computer which belongs to theuser of a mobile device 100 are redirected from the message server 40 tothe mobile device 100 as they are received.

Regardless of the specific mechanism controlling the forwarding ofmessages to the mobile device 100, the message 15, or possibly atranslated or reformatted version thereof, is sent to the wirelessgateway 85. The wireless infrastructure 90 includes a series ofconnections to wireless network 105. These connections could beIntegrated Services Digital Network (ISDN), Frame Relay or T1connections using the TCP/IP protocol used throughout the Internet. Asused herein, the term “wireless network” is intended to include threedifferent types of networks, those being (1) data-centric wirelessnetworks, (2) voice-centric wireless networks and (3) dual-mode networksthat can support both voice and data communications over the samephysical base stations. Combined dual-mode networks include, but are notlimited to, (1) Code Division Multiple Access (CDMA) networks, (2) theGroupe Special Mobile or the Global System for Mobile Communications(GSM) and the General Packet Radio Service (GPRS) networks, and (3)future third-generation (3G) networks like Enhanced Data-rates forGlobal Evolution (EDGE) and Universal Mobile Telecommunications Systems(UMTS). Some older examples of data-centric network include the Mobitex™Radio Network and the DataTAC™ Radio Network. Examples of oldervoice-centric data networks include Personal Communication Systems (PCS)networks like GSM, and TDMA systems.

FIG. 2 is a block diagram of a further example communication systemincluding multiple networks and multiple mobile communication devices.The system of FIG. 2 is substantially similar to the FIG. 1 system, butincludes a host system 30, a redirection program 45, a mobile devicecradle 65, a wireless virtual private network (VPN) router 75, anadditional wireless network 110 and multiple mobile communicationdevices 100. As described above in conjunction with FIG. 1, FIG. 2represents an overview of a sample network topology. Although theencoded message processing systems and methods described herein may beapplied to networks having many different topologies, the network ofFIG. 2 is useful in understanding an automatic e-mail redirection systemmentioned briefly above.

The central host system 30 will typically be a corporate office or otherLAN, but may instead be a home office computer or some other privatesystem where mail messages are being exchanged. Within the host system30 is the message server 40, running on some computer within thefirewall of the host system, that acts as the main interface for thehost system to exchange e-mail with the Internet 20. In the system ofFIG. 2, the redirection program 45 enables redirection of data itemsfrom the server 40 to a mobile communication device 100. Although theredirection program 45 is shown to reside on the same machine as themessage server 40 for ease of presentation, there is no requirement thatit must reside on the message server. The redirection program 45 and themessage server 40 are designed to co-operate and interact to allow thepushing of information to mobile devices 100. In this installation, theredirection program 45 takes confidential and non-confidential corporateinformation for a specific user and redirects it out through thecorporate firewall to mobile devices 100. A more detailed description ofthe redirection software 45 may be found in the commonly assigned U.S.Pat. No. 6,219,694 (“the '694 patent”), entitled “System and Method forPushing Information From A Host System To A Mobile Data CommunicationDevice Having A Shared Electronic Address”, and issued to the assigneeof the instant application on Apr. 17, 2001, which is herebyincorporated into the present application by reference. This pushtechnique may use a wireless friendly encoding, compression andencryption technique to deliver all information to a mobile device, thuseffectively extending the security firewall to include each mobiledevice 100 associated with the host system 30.

As shown in FIG. 2, there may be many alternative paths for gettinginformation to the mobile device 100. One method for loading informationonto the mobile device 100 is through a port designated 50, using adevice cradle 65. This method tends to be useful for bulk informationupdates often performed at initialization of a mobile device 100 withthe host system 30 or a computer 35 within the system 30. The other mainmethod for data exchange is over-the-air using wireless networks todeliver the information. As shown in FIG. 2, this may be accomplishedthrough a wireless VPN router 75 or through a traditional Internetconnection 95 to a wireless gateway 85 and a wireless infrastructure 90,as described above. The concept of a wireless VPN router 75 is new inthe wireless industry and implies that a VPN connection could beestablished directly through a specific wireless network 110 to a mobiledevice 100. The possibility of using a wireless VPN router 75 has onlyrecently been available and could be used when the new Internet Protocol(IP) Version 6 (IPV6) arrives into IP-based wireless networks. This newprotocol will provide enough IP addresses to dedicate an IP address toevery mobile device 100 and thus make it possible to push information toa mobile device 100 at any time. A principal advantage of using thiswireless VPN router 75 is that it could be an off-the-shelf VPNcomponent, thus it would not require a separate wireless gateway 85 andwireless infrastructure 90 to be used. A VPN connection would preferablybe a Transmission Control Protocol (TCP)/IP or User Datagram Protocol(UDP)/IP connection to deliver the messages directly to the mobiledevice 100. If a wireless VPN 75 is not available then a link 95 to theInternet 20 is the most common connection mechanism available and hasbeen described above.

In the automatic redirection system of FIG. 2, a composed e-mail message15 leaving the e-mail sender 10 arrives at the message server 40 and isredirected by the redirection program 45 to the mobile device 100. Asthis redirection takes place the message 15 is re-enveloped, asindicated at 80, and a possibly proprietary compression and encryptionalgorithm can then be applied to the original message 15. In this way,messages being read on the mobile device 100 are no less secure than ifthey were read on a desktop workstation such as 35 within the firewall.All messages exchanged between the redirection program 45 and the mobiledevice 100 preferably use this message repackaging technique. Anothergoal of this outer envelope is to maintain the addressing information ofthe original message except the sender's and the receiver's address.This allows reply messages to reach the appropriate destination, andalso allows the “from” field to reflect the mobile user's desktopaddress. Using the user's e-mail address from the mobile device 100allows the received message to appear as though the message originatedfrom the user's desktop system 35 rather than the mobile device 100.

With reference back to the port 50 and cradle 65 connectivity to themobile device 100, this connection path offers many advantages forenabling one-time data exchange of large items. For those skilled in theart of personal digital assistants (PDAs) and synchronization, the mostcommon data exchanged over this link is Personal Information Management(PIM) data 55. When exchanged for the first time this data tends to belarge in quantity, bulky in nature and requires a large bandwidth to getloaded onto the mobile device 100 where it can be used on the road. Thisserial link may also be used for other purposes, including setting up aprivate security key 111 such as an S/MIME or PGP specific private key,the Certificate (Cert) of the user and their Certificate RevocationLists (CRLs) 60. The private key is preferably exchanged so that thedesktop 35 and mobile device 100 share one personality and one methodfor accessing all mail. The Cert and CRLs are normally exchanged oversuch a link because they represent a large amount of the data that isrequired by the device for S/MIME, PGP and other public key securitymethods.

FIG. 3 depicts a mobile device 100 that is in an unlocked state. Themobile device 100 provides one or more user interface screens 200through which to interact with a user 230 of the device 100. Content inthe form of user field data 220 is provided by the user 230 to fields210 that appear on the user interface screens 200. An example of userfield data 210 can include text or numbers (or combinations thereof)entered by a user 230 into a device's memo pad application.

It is noted that when the device 100 is unlocked, the mobile device 100may keep the device's private key decrypted in a temporary buffer. Themobile device 100 goes into a secure mode when the mobile device 100enters into a locked state. In such a state, the mobile device 100 canerase the temporary buffer that holds the private key.

The device becomes completely secure when it is locked. An indication tothe user that the device has become completely secure can be provided byshowing a lock icon on an information banner of the mobile device 100.The mobile device 100 can be configured to display this icon as soon aspossible after the device enters a locked state so that the user can seethat content protection is working. However, the lock icon may notappear if the device locks while the user is viewing or editing PIMdata, or viewing an e-mail message, or composing an e-mail message(including forwarding and replying to messages). This can arise becausesome of the user's data is stored on screens and is therefore notprotected by content protection.

FIG. 4 depicts a system that addresses such situations by providingcontent protection for data contained in user interface fields 210 forwhen the mobile device 100 enters into a locked state. The contentprotection depicted in FIG. 4 provides a secure mode for the device 100wherein the user-entered data is stored on the device 100 (e.g., inflash memory and/or RAM) in an encrypted form.

For example, user field data 300 is provided to an encryption softwaremodule 310 which places the user field data 300 in an encrypted form320. Such protection counters attacks where an adversary steals a device100, opens the device 100 and uses JTag or similar methods to read thedata directly from the device's flash chip.

With reference to FIG. 5, when a mobile device 100 has become unlocked,the encrypted user field data is decrypted by decryption software module350, thereby reacquiring the user field data 300. The user field data300 is then used to populate one or more user fields 210 that hadappeared on the device's user interface screen(s) 200.

FIG. 6 illustrates an example of an operational scenario for handlinguser field data. At step 400 of the operational scenario, an indicationis received that the mobile device is to enter into a protected mode.User field data that appears on the device's user interface screens arestored in a secure form at step 402.

Later when an indication is received at step 404 that the mobile deviceis leaving or is no longer in a protected mode, the stored secured userfield data is accessed at step 406. The accessed user field data is usedto repopulate at step 408 the user fields that appear on one or more ofthe user interfaces.

FIGS. 7 and 8 illustrate an example of an operational scenario forcreating encryptable fields in order to protect content. With referenceto FIG. 7, a user enters content into one or more fields on a userinterface screen at step 500. The user could also take the defaultvalues of one or more fields. At step 502, the mobile device enters intoa lock mode. The device could have entered the lock mode for manydifferent reasons, such as the mobile device automatically entering thelock mode after a certain period of user inactivity, or the mobiledevice enters the lock mode because of user input.

In this particular operational scenario, when the device is locked, thedevice automatically encrypts the fields' contents at step 504 andstores at step 506 the encrypted data in a data store 508 (e.g., in amember variable). The plain text is cleared from the screen at step 510.Processing for this operational scenario continues at step 514 asindicated by the continuation marker 512.

With reference to FIG. 8, when the device unlocks at step 514, the datain the data store 508 is accessed at step 516 and decrypted 518. Thedecrypted field data is then redisplayed on the proper screens. Throughsuch an approach in this operational scenario, the user's data can beprotected when the device is locked. This also allows, among otherthings, that when the user unlocks their device they are returned to thesame state (e.g., same or substantially similar screen display) thatthey were before the device was locked.

It should be understood that the steps and the order of the stepsdescribed in this operational scenario may be altered, modified and/oraugmented and still achieve the desired outcome. For example, theoperational scenario can also include not having to close an applicationwhen the device enters a locked state. As another example, the fielddata can be secured in many different ways, such as through use ofsymmetric cryptographic key techniques, asymmetric cryptographic keyencryption techniques, or combinations thereof.

FIG. 9 depicts an example of a user interface screen 550 that could bedisplayed to a user of a mobile device. The user interface screen 550 ofthe example is a screen containing task PIM fields for display to theuser. The user interface screen 550 contains a task name field 552, atask status field 554, a task priority field 556, a task due date field558, and a task notes field 560. A task screen can have more or lessfields than what is shown in FIG. 9.

One or more of the fields (552, 554, 556, 558, 560) may have defaultvalues already in the field value entry region. For example, the taskpriority field 556 may be pre-populated with a “normal” task priorityvalue. A user can elect to change a default value if so desired.

If the mobile device enters a lock mode, then the values appearing inthe fields (552, 554, 556, 558, 560) will be stored in a secure form andused after the mobile device is unlocked to repopulate the fields (552,554, 556, 558, 560) with the values. The mobile device can be configuredto automatically display the user interface screen 550 with the valuesafter the mobile device is unlocked.

The systems and methods disclosed herein are presented only by way ofexample and are not meant to limit the scope of the invention. Othervariations of the systems and methods described above will be apparentto those skilled in the art and as such are considered to be within thescope of the invention. As an example, a system and method can beconfigured to receive input which indicates that the mobile device is toenter into a protected mode. Data associated with fields displayed on auser interface are stored in a secure manner on the mobile device. Thiscould include that when a device is placed into a protected mode (e.g.,a locked state), data in the device's user interface fields is stored inan encrypted form. After the mobile device leaves the protected mode,the stored user interface field data is accessed and used to populateone or more user interface fields with the accessed user interface fielddata for display to a user.

As another example, a system and method can be configured for operationupon a mobile device that is capable of displaying interfaces to a user.Input is received which indicates that the mobile device is to enterinto a protected mode. Data associated with fields displayed on a userinterface is encrypted and stored in a data store. After the mobiledevice leaves the protected mode, the stored encrypted user interfacefield data is decrypted and used to populate one or more user interfacefields for display to a user.

As another example, a system and method can be configured to includefirst software instructions that are configured to encrypt dataassociated with fields displayed on a user interface. The field dataencryption is in response to input being received which indicates thatthe mobile device is to enter into a protected mode. A data store isused to store on the mobile device the encrypted user interface fielddata. Second software instructions are configured to decrypt the storedencrypted user interface field data in response to the mobile deviceleaving the protected mode. The one or more user interface fields arepopulated with the decrypted user interface field data for display to auser.

As yet another example, a content protection scheme can include closingany screens that contain user data. Once the screens are closed thefields can release the plaintext data, which can be garbage collectedand zero'ed, thus securing the device. As another example, a contentprotection scheme could include specifying that the user should returnto a main application screen before locking their device.

Still further, the systems and methods disclosed herein may be used withmany different computers and devices, such as a wireless mobilecommunications device shown in FIG. 10. With reference to FIG. 10, themobile device 100 is a dual-mode mobile device and includes atransceiver 611, a microprocessor 638, a display 622, non-volatilememory 624, random access memory (RAM) 626, one or more auxiliaryinput/output (I/O) devices 628, a serial port 630, a keyboard 632, aspeaker 634, a microphone 636, a short-range wireless communicationssub-system 640, and other device sub-systems 642.

The transceiver 611 includes a receiver 612, a transmitter 614, antennas616 and 618, one or more local oscillators 613, and a digital signalprocessor (DSP) 620. The antennas 616 and 618 may be antenna elements ofa multiple-element antenna, and are preferably embedded antennas.However, the systems and methods described herein are in no wayrestricted to a particular type of antenna, or even to wirelesscommunication devices.

The mobile device 100 is preferably a two-way communication devicehaving voice and data communication capabilities. Thus, for example, themobile device 100 may communicate over a voice network, such as any ofthe analog or digital cellular networks, and may also communicate over adata network. The voice and data networks are depicted in FIG. 10 by thecommunication tower 619. These voice and data networks may be separatecommunication networks using separate infrastructure, such as basestations, network controllers, etc., or they may be integrated into asingle wireless network.

The transceiver 611 is used to communicate with the network 619, andincludes the receiver 612, the transmitter 614, the one or more localoscillators 613 and the DSP 620. The DSP 620 is used to send and receivesignals to and from the transceivers 616 and 618, and also providescontrol information to the receiver 612 and the transmitter 614. If thevoice and data communications occur at a single frequency, orclosely-spaced sets of frequencies, then a single local oscillator 613may be used in conjunction with the receiver 612 and the transmitter614. Alternatively, if different frequencies are utilized for voicecommunications versus data communications for example, then a pluralityof local oscillators 613 can be used to generate a plurality offrequencies corresponding to the voice and data networks 619.Information, which includes both voice and data information, iscommunicated to and from the transceiver 611 via a link between the DSP620 and the microprocessor 638.

The detailed design of the transceiver 611, such as frequency band,component selection, power level, etc., will be dependent upon thecommunication network 619 in which the mobile device 100 is intended tooperate. For example, a mobile device 100 intended to operate in a NorthAmerican market may include a transceiver 611 designed to operate withany of a variety of voice communication networks, such as the Mobitex orDataTAC mobile data communication networks, AMPS, TDMA, CDMA, PCS, etc.,whereas a mobile device 100 intended for use in Europe may be configuredto operate with the GPRS data communication network and the GSM voicecommunication network. Other types of data and voice networks, bothseparate and integrated, may also be utilized with a mobile device 100.

Depending upon the type of network or networks 619, the accessrequirements for the mobile device 100 may also vary. For example, inthe Mobitex and DataTAC data networks, mobile devices are registered onthe network using a unique identification number associated with eachmobile device. In GPRS data networks, however, network access isassociated with a subscriber or user of a mobile device. A GPRS devicetypically requires a subscriber identity module (“SIM”), which isrequired in order to operate a mobile device on a GPRS network. Local ornon-network communication functions (if any) may be operable, withoutthe SIM device, but a mobile device will be unable to carry out anyfunctions involving communications over the data network 619, other thanany legally required operations, such as ‘911’ emergency calling.

After any required network registration or activation procedures havebeen completed, the mobile device 100 may the send and receivecommunication signals, including both voice and data signals, over thenetworks 619. Signals received by the antenna 616 from the communicationnetwork 619 are routed to the receiver 612, which provides for signalamplification, frequency down conversion, filtering, channel selection,etc., and may also provide analog to digital conversion. Analog todigital conversion of the received signal allows more complexcommunication functions, such as digital demodulation and decoding to beperformed using the DSP 620. In a similar manner, signals to betransmitted to the network 619 are processed, including modulation andencoding, for example, by the DSP 620 and are then provided to thetransmitter 614 for digital to analog conversion, frequency upconversion, filtering, amplification and transmission to thecommunication network 619 via the antenna 618.

In addition to processing the communication signals, the DSP 620 alsoprovides for transceiver control. For example, the gain levels appliedto communication signals in the receiver 612 and the transmitter 614 maybe adaptively controlled through automatic gain control algorithmsimplemented in the DSP 620. Other transceiver control algorithms couldalso be implemented in the DSP 620 in order to provide moresophisticated control of the transceiver 611.

The microprocessor 638 preferably manages and controls the overalloperation of the mobile device 100. Many types of microprocessors ormicrocontrollers could be used here, or, alternatively, a single DSP 620could be used to carry out the functions of the microprocessor 638.Low-level communication functions, including at least data and voicecommunications, are performed through the DSP 620 in the transceiver611. Other, high-level communication applications, such as a voicecommunication application 624A, and a data communication application624B may be stored in the non-volatile memory 624 for execution by themicroprocessor 638. For example, the voice communication module 624A mayprovide a high-level user interface operable to transmit and receivevoice calls between the mobile device 100 and a plurality of other voiceor dual-mode devices via the network 619. Similarly, the datacommunication module 624B may provide a high-level user interfaceoperable for sending and receiving data, such as e-mail messages, files,organizer information, short text messages, etc., between the mobiledevice 100 and a plurality of other data devices via the networks 619.

The microprocessor 638 also interacts with other device subsystems, suchas the display 622, the RAM 626, the auxiliary input/output (I/O)subsystems 628, the serial port 630, the keyboard 632, the speaker 634,the microphone 636, the short-range communications subsystem 640 and anyother device subsystems generally designated as 642.

Some of the subsystems shown in FIG. 10 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as the keyboard 632 and thedisplay 622 may be used for both communication-related functions, suchas entering a text message for transmission over a data communicationnetwork, and device-resident functions such as a calculator or task listor other PDA type functions.

Operating system software used by the microprocessor 638 is preferablystored in a persistent store such as non-volatile memory 624. Thenon-volatile memory 624 may be implemented, for example, as a Flashmemory component, or as battery backed-up RAM. In addition to theoperating system, which controls low-level functions of the mobiledevice 610, the non-volatile memory 624 includes a plurality of softwaremodules 624A-624N that can be executed by the microprocessor 638 (and/orthe DSP 620), including a voice communication module 624A, a datacommunication module 624B, and a plurality of other operational modules624N for carrying out a plurality of other functions. These modules areexecuted by the microprocessor 638 and provide a high-level interfacebetween a user and the mobile device 100. This interface typicallyincludes a graphical component provided through the display 622, and aninput/output component provided through the auxiliary I/O 628, keyboard632, speaker 634, and microphone 636. The operating system, specificdevice applications or modules, or parts thereof, may be temporarilyloaded into a volatile store, such as RAM 626 for faster operation.Moreover, received communication signals may also be temporarily storedto RAM 626, before permanently writing them to a file system located ina persistent store such as the Flash memory 624.

An exemplary application module 624N that may be loaded onto the mobiledevice 100 is a personal information manager (PIM) application providingPDA functionality, such as calendar events, appointments, and taskitems. This module 624N may also interact with the voice communicationmodule 624A for managing phone calls, voice mails, etc., and may alsointeract with the data communication module for managing e-mailcommunications and other data transmissions. Alternatively, all of thefunctionality of the voice communication module 624A and the datacommunication module 624B may be integrated into the PIM module.

The non-volatile memory 624 preferably also provides a file system tofacilitate storage of PIM data items on the device. The PIM applicationpreferably includes the ability to send and receive data items, eitherby itself, or in conjunction with the voice and data communicationmodules 624A, 624B, via the wireless networks 619. The PIM data itemsare preferably seamlessly integrated, synchronized and updated, via thewireless networks 619, with a corresponding set of data items stored orassociated with a host computer system, thereby creating a mirroredsystem for data items associated with a particular user.

Context objects representing at least partially decoded data items, aswell as fully decoded data items, are preferably stored on the mobiledevice 100 in a volatile and non-persistent store such as the RAM 626.Such information may instead be stored in the non-volatile memory 624,for example, when storage intervals are relatively short, such that theinformation is removed from memory soon after it is stored. However,storage of this information in the RAM 626 or another volatile andnon-persistent store is preferred, in order to ensure that theinformation is erased from memory when the mobile device 100 losespower. This prevents an unauthorized party from obtaining any storeddecoded or partially decoded information by removing a memory chip fromthe mobile device 100, for example.

The mobile device 100 may be manually synchronized with a host system byplacing the device 100 in an interface cradle, which couples the serialport 630 of the mobile device 100 to the serial port of a computersystem or device. The serial port 630 may also be used to enable a userto set preferences through an external device or software application,or to download other application modules 624N for installation. Thiswired download path may be used to load an encryption key onto thedevice, which is a more secure method than exchanging encryptioninformation via the wireless network 619. Interfaces for other wireddownload paths may be provided in the mobile device 100, in addition toor instead of the serial port 630. For example, a USB port would providean interface to a similarly equipped personal computer.

Additional application modules 624N may be loaded onto the mobile device100 through the networks 619, through an auxiliary I/O subsystem 628,through the serial port 630, through the short-range communicationssubsystem 640, or through any other suitable subsystem 642, andinstalled by a user in the non-volatile memory 624 or RAM 626. Suchflexibility in application installation increases the functionality ofthe mobile device 100 and may provide enhanced on-device functions,communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using the mobiledevice 100.

When the mobile device 100 is operating in a data communication mode, areceived signal, such as a text message or a web page download, isprocessed by the transceiver module 611 and provided to themicroprocessor 638, which preferably further processes the receivedsignal in multiple stages as described above, for eventual output to thedisplay 622, or, alternatively, to an auxiliary I/O device 628. A userof mobile device 100 may also compose data items, such as e-mailmessages, using the keyboard 632, which is preferably a completealphanumeric keyboard laid out in the QWERTY style, although otherstyles of complete alphanumeric keyboards such as the known DVORAK stylemay also be used. User input to the mobile device 100 is furtherenhanced with a plurality of auxiliary I/O devices 628, which mayinclude a thumbwheel input device, a touchpad, a variety of switches, arocker input switch, etc. The composed data items input by the user maythen be transmitted over the communication networks 619 via thetransceiver module 611.

When the mobile device 100 is operating in a voice communication mode,the overall operation of the mobile device is substantially similar tothe data mode, except that received signals are preferably be output tothe speaker 634 and voice signals for transmission are generated by amicrophone 636. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on the mobiledevice 100. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 634, the display 622 may alsobe used to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information. Forexample, the microprocessor 638, in conjunction with the voicecommunication module and the operating system software, may detect thecaller identification information of an incoming voice call and displayit on the display 622.

A short-range communications subsystem 640 is also included in themobile device 100. The subsystem 640 may include an infrared device andassociated circuits and components, or a short-range RF communicationmodule such as a Bluetooth™ module or an 802.11 module, for example, toprovide for communication with similarly-enabled systems and devices.Those skilled in the art will appreciate that “Bluetooth” and “802.11”refer to sets of specifications, available from the Institute ofElectrical and Electronics Engineers, relating to wireless personal areanetworks and wireless local area networks, respectively.

The systems' and methods' data may be stored in one or more data stores.The data stores can be of many different types of storage devices andprogramming constructs, such as RAM, ROM, Flash memory, programming datastructures, programming variables, etc. It is noted that data structuresdescribe formats for use in organizing and storing data in databases,programs, memory, or other computer-readable media for use by a computerprogram.

The systems and methods may be provided on many different types ofcomputer-readable media including computer storage mechanisms (e.g.,CD-ROM, diskette, RAM, flash memory, computer's hard drive, etc.) thatcontain instructions for use in execution by a processor to perform themethods' operations and implement the systems described herein.

The computer components, software modules, functions and data structuresdescribed herein may be connected directly or indirectly to each otherin order to allow the flow of data needed for their operations. It isalso noted that a module or processor includes but is not limited to aunit of code that performs a software operation, and can be implementedfor example as a subroutine unit of code, or as a software function unitof code, or as an object (as in an object-oriented paradigm), or as anapplet, or in a computer script language, or as another type of computercode.

1. A method for operation upon a mobile device that is capable ofdisplaying interfaces to a user, comprising: receiving input whichindicates that the mobile device is to enter into a protected mode;encrypting data associated with fields displayed on a user interface;storing on the mobile device the encrypted user interface field data;wherein after the mobile device leaves the protected mode, decryptingthe stored encrypted user interface field data; populating one or moreuser interface fields with the decrypted user interface field data fordisplay to a user.
 2. The method of claim 1, wherein entering theprotected mode includes locking the mobile device.
 3. The method ofclaim 1, wherein the user of the mobile device interacts with the userinterface in order to enter values into one or more of the fieldsdisplayed on the user interface; wherein the user entered field valuesare the data that is encrypted during said encrypting step.
 4. Themethod of claim 3, wherein the values are numeric values, textualvalues, or combinations thereof.
 5. The method of claim 1, wherein aprivate key is used to encrypt the user interface field data during saidencrypting step.
 6. The method of claim 5, wherein the private key isstored in a temporary buffer of the mobile device, said method furthercomprising: when the mobile device enters into the secure mode, theprivate key is erased from the temporary buffer.
 7. The method of claim1, wherein a lock icon is displayed to the user when the mobile deviceis in the secure mode; wherein the lock icon indicates that data on themobile device is protected based upon the user interface field datahaving been encrypted and stored on the mobile device.
 8. The method ofclaim 7, wherein the lock icon is displayed despite the device lockingwhile the user was viewing or editing field data on the user interface.9. The method of claim 1, wherein the encrypted user interface fielddata is stored in an encrypted form in the mobile device's flash memoryor random access memory (RAM).
 10. The method of claim 9, wherein theencrypted form is used to counter attacks on the mobile device whereinan attempt is made to read data directly from the device's flash memoryor RAM.
 11. The method of claim 1 further comprising: displaying to theuser the user interface that is populated with the decrypted userinterface field data, thereby allowing the mobile device to return tothe same user interface screen that was displayed to the user before thedevice entered into the protected mode.
 12. The method of claim 1,wherein the input indicating that the mobile device is to enter into aprotected mode is generated after a certain period of user inactivity orbecause of user input.
 13. The method of claim 1, wherein plain text iscleared from the mobile device's screen based upon the mobile deviceentering into the protected mode.
 14. The method of claim 1, wherein theencrypting and decrypting of the user interface field data are performedusing an asymmetric cryptographic technique, a symmetric cryptographictechnique, or combinations thereof.
 15. The method of claim 1, whereinthe user interface field data includes PIM (Personal InformationManagement) data associated with the user of the mobile device.
 16. Themethod of claim 1, wherein the application associated with the userinterface is not closed when the mobile device enters the protectedmode.
 17. The method of claim 1, wherein when the mobile device is toenter into the protected mode, any screens containing user data areclosed; wherein after the screens are closed and the encrypted fielddata is stored, the field data associated with the user interface isreleased and garbage collected.
 18. The method of claim 1, wherein themobile device returns to a main application screen before the mobiledevice enters into the protected mode.
 19. The method of claim 1,wherein the mobile device is a wireless mobile communications device ora personal digital assistant (PDA) that receives messages over awireless communication network.
 20. Computer software program orprograms stored on one or more computer readable media, the computersoftware program or programs comprising program code for carrying out amethod according to claim
 1. 21. A system for operation upon a mobiledevice that is capable of displaying interfaces to a user, comprising:first software instructions configured to encrypt data associated withfields displayed on a user interface in response to input being receivedwhich indicates that the mobile device is to enter into a protectedmode; a data store to store on the mobile device the encrypted userinterface field data; second software instructions configured to decryptthe stored encrypted user interface field data in response to the mobiledevice leaving the protected mode; wherein one or more user interfacefields are populated with the decrypted user interface field data fordisplay to a user.
 22. A method for operation upon a mobile device thatis capable of displaying interfaces to a user, comprising: receivinginput which indicates that the mobile device is to enter into aprotected mode; storing, in a secure from on the mobile, data associatedwith fields displayed on a user interface; wherein after the mobiledevice leaves the protected mode, accessing the stored user interfacefield data; populating one or more user interface fields with theaccessed user interface field data for display to a user.